Method of forming receptacles



Aug. 8, 1950 o. MAPES ETAL METHOD OF FORMING RECEPTACLES Filed Oct. 26, 1946 Bnvemtors Daniel Mapes 55.... 0/////////fl/////////////////////J Walter G. Sylves ter Ralph P Hayes WM CLMW attorneg Patented Aug. 8, 1950 METHOD OF FORMING RECEP'I'ACLES Daniel Manes, West Caldwell, Walter G. Sylvester, Jersey City, and Ralph P. Hayes, Orange, N. J assignors to Specialties Development Corporatron, Belleville, N. J., a corporation of New Jersey Application October 26, 1946, Serial N0. 705,932

3 Claims.

rue present invention relates to methods of iorming metallic receptacles, and more particularly to the provision of receptacles formed of a metal which has one heat conductive characteristic having a layer of metal at the bottom thereof which has another heat conductive characteristic.

The invention is concerned with, but not limited to, the formation of stainless steel recep-' tacles, which have poor heat conductive characteristics, having a relatively thick layer of copper on the bottom thereof adapted to render the bottom of the receptacle highly heat conductive. The layer of copper covers the bottom of the receptacle and extends around the curved corner portions joining the bottom and side walls of the receptacle. The layer is substantially of uniform thickness at the bottom and is of gradually diminishing thickness at the corner portions.

Heretofore receptacles of the foregoing type have been made by electroplating layers of copper to the bottom of stainless steel receptacles. The methods employed in forming such layers necessitated complicated electroplating apparatus and chemical treatments which required accurate controls or highly skilled labor. Also, the quantity of current required to so electroplate the receptacles was substantially high and made the process relatively expensive.

An object of the present invention is to provide a novel, inexpensive method of making receptacles of the foregoing character.

Another object is to provide a simple method of making such receptacles which does not require complicated apparatus or controls and can be performed by unskilled labor.

Another object is to provide a method of making such receptacles wherein the dimensions of the layer on the bottom are accurately controlled in a simple manner.

A further object is to prevent distortion of the bottom of the receptacle while the layer is applied thereto.

Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

In accordance with the invention, the foregoing objects and advantages are accomplished by forming a sheet-metal blank having a depressed central portion, establishing a pool of molten metal in the depressed central portion, solidfying the molten metal and bonding the same to the blank, and re-forming the central portion to provide a substantially fiat bottom for a receptacle having a layer of metal at the underside thereof. In order to provide a side wall for the receptacle, the central portion is surrounded by an annular marginal portion which is re-formed after the layer of metal is bonded to the blank. This marginal portion preferably extends downwardly with respect to the depressed central portion.

In the accompanying drawing:

Figure 1 is a side elevational view illustrating a receptacle in the form of a cooking pot embodying the present invention.

Figure 2 is a side elevational view illustrating a receptacle in the form of a frying pan or skillet embodying the present invention.

Figure 3 is a plan view of a metallic disc adapted to be formed into a receptacle.

Figure 3a is a sectional view of the disc taken along the line Clo-3a on Figure 3.

Figure 4 is a sectional view illustrating the disc drawn into a cup-shaped blank.

Figure 5 is a sectional view illustrating the blank formed with a depressed central portion, the annular marginal portion extending downwardly with respect to the depressed portion.

Figure 6 is a sectional view of the blank shown in Figure 5 with a pool of molten metal established in the depressed portion and the blank supported for the bonding operation.

Figure 7 is a sectional view illustrating the blank after being re-formed to provide a receptacle body having a fiat bottom, with the layer of metal bonded to the underside thereof and having tall side walls.

Figure 8 is a sectional view of a modified blank provided with a raised dome portion at the center of the depression.

Figure 9 is a sectional view illustrating a receptacle body having a flat bottom with the layer of metal bonded to the underside thereof and having short side walls.

Referring to the drawings in detail and more particularly to Figure 1, there is shown a receptacle in the form of a deep cooking p ot l0 having carrying handles ll secured thereto. The body of the pot is formed of stainless steel and the bottom portion thereof has bonded thereto a layer of copper I2 which is of substantially uniform thickness at the bottom and gradually diminishes in thickness at the rounded corner joining the bottom and the side wall of the pot (Figure 7). While stainless steel is a poor conductor of heat, the high heat conductivity of the copper layer makes the bottom of the pot highly heat conductive and tends to uniformly distribute the heat transferred through the layer of stainless steel.

In Figure 2 a stainless steel receptacle is shown in the form of a frying pan or skillet Illa having a handle I la secured thereto and having a layer of copper |2a at the bottom portion thereof.

The receptacles shown in Figures 1 and 2 illustrate, by way of example, articles adapted to be formed by employing the methods of the present invention, it being understood that the invention is applicable to other forms of cooking vessels or utensils and to receptacles utilized for other purposes.

The method of forming the receptacle shown in Figure 1 is illustrated more particularly in Figures 3 to 'I. This method comprises forming a substantially circular disc or blank |'5 (Figures 3 and 3a) from a sheet of stainless steel and drawing the blank l5 into a cup l6 (Figure 4) having a bottom l1 and an annular marginal portion in the form of a side wall i9 surrounding the bottom. During the drawing operation or by a subsequent operation, the bottom i1 is formed with a circular depressed central portion 20 and an annular downwardly and inwardly inclined zone 2|, as viewed in Figure 5, to provide a recess 22. and the side wall I9.

In order to apply a copper layer, the cup I6 is placed on a tubular cylindrical support or ring 24 which engages the rounded portions 23 at the interior of the cup as shown in Figure 6. The support is placed on a surface 25, which may be the floor of a furnace or a conveyor adapted to move the support 24 through a furnace. It will be noted that the support 24 is of a height to maintain the free edge of the side Wall l9 out of contact with the surface 25.

A charge 26 comprising metallic copper in any suitable form and a suitable brazing flux is placed in the recess 22. The charge is heated by placing the support 24 with the cup I6 thereon in a furnace supplied with a reducing atmosphere and maintained at a temperature to melt the copper and thereby to establish a pool of molten copper in the recess.

The temperature in the furnace is reduced to a desired value while maintaining the reducing atmosphere. At this temperature the charge becomes solidified and the stainless steel can be quenched to retain its annealed state to facilitate further drawing thereof.

The cup is then redrawn to reduce its diameter and to elongate its side wall l9. This is accomplished by shaping the corner portions 23 and the outer peripheral portion of the zone 2| into a portion of the side wall; shaping the remainder of the zone 2| and the outer peripheral zone of the central portion 20 into rounded corner portions 3 I and shaping the remainder of the central portion into a flat bottom 30 joined to the side wall H! by the rounded portions 3|, as shown in Figure 7.

The body of the receptacle l so shaped will have a layer of copper of substantially uniform thickness at its bottom 30, while the corner portions 3| will have a layer of copper diminishing in thickness in the direction approaching the side wall l9.

By way of example, the blank I may have a diameter of about sixteen inches and a thickness of about one-sixteenth of an inch. The cup l6 shaped from the blank will have a diameter of about eight inches and a height of about four and one-half inches. The depressed portion may Rounded corner portions 23 join the zone 2| have a diameter of about five inches and the annular zone 2! may have a width of about one inch, being inclined with respect to the portion 20 at about twenty degrees to provide a recess 22 having a depth of about one-quarter of an inch. The rounded corner portions 23 joining the side wall l9 and the zone 2| may have a radius of about one-half of an inch.

The charge 26 of copper and brazing flux placed in recess 22 may weigh about one pound and provides a pool of molten metal having a depth of about three-sixteenths of an inch. When the cup I6 is redrawn to the shape shown in Figure 7 it has a diameter of about six inches and a height of about flve and one-half inches. The layer of copper l2 at the underside of the bottom 30 will have a thickness of about three-sixteenths of an inch. It will be understood that where a thicker or thinner layer of copper is desired the weight of the charge may be varied accordingly.

Referring to Figure 8, there is shown a cup I6 formed with a modified depressed central portion having a substantially shallow dome 200. By being so shaped the recessed bottom of the cup is strengthened to prevent sagging thereof at temperatures to which the cup is subjected while in the furnace to melt the charge 26.

By increasing the height of the dome a layer of copper of a desired varying thickness may be doposited on the bottom or a layer may be deposited which is in the form 059. ring to concentrate the heat transferred at the peripheral portions of the bottom.

The receptacle Illa shown in Figure 2 may be formed by practicing the methods described in connection with Figures 3 to 8 inclusive and thereafter cutting away a portion of the side wall l9 to provide a receptacle body having a side wall 36 of a desired height, as shown in Figure 9.

While the present invention has been described in connection with depositing a layer of copper on stainless steel, it will be understood that the methods described herein can be utilized for bonding a layer f other nonferrous metals to a receptacle body formed of other ferrous or nonferrous metals.

From the foregoing description, it will be seen that the present invention provides a novel, practical and economical method of applying a layer of metal to receptacle body formed of another metal. The shape of the recess is such that a charge of metal and flux can be readily melted and solidified therein to provide a smooth deposit of sound metal, which layer upon re-forming of the receptacle body remains securely'bonded thereto, is of a desired thickness at the bottom and side wall of the receptacle. The contour of the cup or blank formed with the recess for receiving the charge permits controlled expansion and contraction thereof during the brazing step, thus maintaining control over the dimensions of the cup or blank and the quantity and distribution of the metal brazed thereon.

By practicing the methods described herein, improved receptacles, such as cooking utensils and the like, can be produced in a, rapid and inexpensive manner. These receptacles are light in weight, rug ed in construction, and can readily withstand any rough usage to which they may ed as illustrative and not in any limiting sense.

It is also to be understood that the following claims are intended to cover all the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

We claim:

1. The method of forming receptacles, which comprises forming a generally circular sheet metal blank of substantially uniform thickness having an annular inwardly and downwardly extending zone and having a central depressed portion surrounded by the zone, establishing a pool of molten metal on the blank of a depth to cover the central portion and to at least partially cover the annular zone, solidifying the molten metal to cause the same to be bonded to the blank, and drawing the annular zone to form a curved annular corner and a side wall portion of smaller diameter than that of the blank, the annular zone being drawn in a direction whereby the central portion constitutes the exterior of the bottom of a receptacle and the corner portion is provided at its exterior with a layer of bonded metal diminishing in thickness from the bottom to the wall portion.

2. The method of forming receptacles, which comprises forming a cup-shaped sheet metal blank of substantially uniform thickness having a side wall and a bottom provided with an annular inwardly and downwardly extending inelin'ed zone and a central depressed portion surrounded by the zone, establishing a pool of molten metal on the blank of a depth to cover the central portion and to at least partially cover the annular zone, solidifying the molten metal to cause the same to be bonded to the blank, and drawing r receptacle and the corner portion is provided at its exterior with a layer of bonded metal diminishing in thickness from the bottom to the side wall.

3. The method of forming receptacles, which comprises forming a cup-shaped sheet metal blank of substantially uniform thickness havin a side wall and a bottom provided at the exterior thereof with an annular inwardly and downwardly extending inclined zone and a central depressed portion surrounded by the zone, establishing a pool of molten metal on the blank of a depth to cover the central portion and to at least partially cover the annular zone, solidifying the molten metal to cause the same to be bonded to the blank, and drawing the blank to reduce its diameter and to form the inclined zone into a curved annular corner and a portion of the side wall, the blank being drawn in a direction to push the bottom outwardly with respect to the side wall whereby the central portion constitutes the exterior of the bottom of a receptacle and the corner portion is provided at its exterior with a layer of bonded metal diminishing in thickness from the bottom to the side wall.

DANIEL MAPES. WALTER G. SYLVES'I'ER. RALPH P. HAYES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,879,212 Hainlen Sept. 27, 1932 2,272,609 Kennedy Feb. 10, 1942 2,359,477 Hoern Oct. 3, 1944 FOREIGN PATENTS Number Country Date 338,211 Germany June 16, 1921 

